Well, I don't know where you'd get small enough rapiers or pistols, but it's generally best to discourage your frogs from fighting. You should definitely break up any race wars that may be occurring in your tanks between species

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Seriously though, why bother dividing one tank into two when you could just have 2 tanks? Even if you did divide a tank, you'd want everything (water system, food, etc.) to be totally isolated if you're putting different species on either side, so I don't see much in the way of savings and I see lots of potential for problems.